Git 2.7.0 gitignore behaviour regression

Hi folks,

Firstly, thanks for all your hard work on Git. It makes my life much easier.

Homebrew has a series of convoluted .gitignore rules due to our special/weird use-case of wanting to ignore everything in a working directory except a select few files/directories. We experienced a bug with our .gitignore file for users using Git 2.7.0. This may well be a valid WONTFIX or intentional behaviour change but I wanted to flag it in case it wasn’t.

Here’s a minimal test case:

- Create an empty git repository in a directory with `git init`
- Create a directory named ‘a' containing a file named ‘b' with `mkdir a && touch a/b`
- Create a ‘gitignore’ file with the following contents:
```
*/
/a
!/a/*
```
- Run `git status --short`.

The output with Git 2.6.4 is: ``` ?? .gitignore ```

The output with Git 2.7.0 is: ``` ?? .gitignore ?? a/ ```

Another minimal test case:

- Create an empty git repository in a directory with `git init`
- Create a directory named ‘a' containing a file named ‘b' with `mkdir a && touch a/b`
- Create a ‘gitignore’ file with the following contents:
```
*/
/a
!/a/
```
- Run `git status —short`.

The output with Git 2.6.4 is: ``` ?? .gitignore ?? a/ ```

The output with Git 2.7.0 is: ``` ?? .gitignore ```

Let me know if you need any more information, thanks!

Mike McQuaid http://mikemcquaid.com